The proliferation of mixed-member electoral systems has progressively led scholars to abandon the dichotomy between majoritarian and proportional systems. Among these numerous variants of these mixed systems, electoral systems with majority bonus remain overlooked and not well understood, not least because of the absence of systematic empirical comparison between them.
France and Italy offer are among the few countries which have implemented mixed-member electoral systems with majority bonuses at several levels of elections. France adopted a proportional electoral system with two rounds and a majority bonus of 25 of the seats in 2003 for the regional elections and has used a system with majority bonus for the municipal election since 1983. Italy has used variants of mixed-member proportional systems with majority bonus at the provincial, regional, and even at the national level since 2005.
These systems are complex, and offer varying aspects in terms of bonus size, number of rounds (one or two), and type of election (local or national). This provides quasi-natural experiments conditions to test for the specific aspects of complex electoral systems on party strategies.
This study focuses specifically on the matter of pre-electoral coalition formation in mixed-member systems with majority bonus. Two main aspects are studied. Firstly, what are effects of bonuses arrangements on the probability of pre-electoral coalitions among parties? We assume here a tradeoff between securing the majority bonus and declining returns in expanding coalition size. Secondly, what are the types of agreements reached in case of coalition formation? Does the well known ‘Gamson law’ of proportional sharing hold in such a context?
Ultimately, this empirical research should lead to the formulation of a theory linking complexity of the electoral systems and the absence of a dominant electoral strategy for political parties.
This proposal is based on a comprehensive database of electoral results of national and local elections in France and Italy. Supplementary materials are provided by Sona Golder’s database on pre-electoral coalition formation.
